vendor: omni: Do not enable telephony-ext as a global feature

this feature is breaking DEX_PREOPT on Sony AOSP devices.
So, do not enable it as a global feature although it is still
a default one.

Devices that are not compat with telephony-ext should
use this flag below before Omni common.mk inclusion.

BOARD_USES_TELEPHONY_EXTENSION := false

Example:
    https://gerrit.omnirom.org/#/c/22443/

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: Iba82fa7072cd85361917705eaea53de5290747de
diff --git a/config/common.mk b/config/common.mk
index 5f0e32e..40815f0 100644
--- a/config/common.mk
+++ b/config/common.mk
@@ -17,6 +17,10 @@
     ro.com.google.clientidbase=$(PRODUCT_GMS_CLIENTID_BASE)
 endif
 
+ifeq ($strip ($BOARD_USES_TELEPHONY_EXTENSION),)
+BOARD_USES_TELEPHONY_EXTENSION := true
+endif
+
 # general properties
 PRODUCT_PROPERTY_OVERRIDES += \
     ro.url.legal=http://www.google.com/intl/%s/mobile/android/basic/phone-legal.html \
diff --git a/config/packages.mk b/config/packages.mk
index e0089b8..232794d 100644
--- a/config/packages.mk
+++ b/config/packages.mk
@@ -42,8 +42,10 @@
     fsck.ntfs
 
 # Telephony extension
+ifeq ($strip ($BOARD_USES_TELEPHONY_EXTENSION),true)
 PRODUCT_PACKAGES += telephony-ext
 PRODUCT_BOOT_JARS += telephony-ext
+endif
 
 # OMS support
 PRODUCT_PACKAGES += ThemeInterfacer